1. Field of the Invention
The present invention relates to a cooling device and a cooling system for cooling a data center comprising a plurality of computer servers, and in addition, to an auxiliary cooling device for cooling the data center in case a main cooling device cannot be used to cool the data center.
2. Discussion of the Related Art
A computer server comprises a plurality of exothermic electronic components arranged on a printed-circuit board, and those electronic components produce heat as a result of being energized to carry out data processing. Therefore, a temperature in a datacenter in which a plurality of servers is installed is raised by the heat of the electronic components. The temperature in the datacenter thus raised is conventionally lowered using an air conditioner thereby cooling the heated electronic components of the servers. In addition, the electronic components itself are cooled directly or indirectly by a refrigerant such as water, brine, etc. cooled by a chiller unit. However, since the data processing of the electronic components is carried out ceaselessly, the chiller unit has to be operated ceaselessly too. Therefore, electric consumption of the air conditioner, and a load on the chiller unit for cooling the refrigerant are increased according to an increase in an amount of the heat generated by the electronic components. As a result, a running cost of the data center increases. In order to avoid such an increase in the running cost of the data center, it is necessary to downsize the cooling system of the data center.
In addition, a backup cooling system composed mainly of a chiller unit is used in the prior art for the purpose of cooling the data center in case the air conditioner or a main chiller unit is out of order, or in case of a power outage. The backup cooling system of this kind is configured to prepare cool water by the chiller unit, and the prepared cool water is reserved in the backup cooling system to be used for cooling the data center in case of aforementioned emergency situation. Specifically, the cool water of 5 to 8 degrees is reserved in the backup cooling system in an amount sufficient to cool the data center for about six hours. Thus, the conventional backup cooling system has to be large enough to continuously contain such a large amount of water. In addition to the above-explained disadvantage, a large electricity cost is required to operate the chiller unit continuously. Therefore, it is necessary to downsize the conventional backup cooling system, and reduce the cost of running the system.
For example, an energy-saving cold storage comprising an ice making pit arranged underneath the storage is disclosed in Japanese Patent Laid-Open No. 60-207877. According to the teachings of Japanese Patent Laid-Open No. 60-207877, the ice making pit is configured to freeze water reserved therein in winter time by dissipating heat of the water to the atmosphere using a heat pipe penetrating through the storage. Therefore, an inner space of the storage can be cooled by cold energy of the ice without running cost.
Japanese Patent Laid-Open No. 2002-372354 discloses a cooling system capable of saving on power consumption and cost. According to the teachings of Japanese Patent Laid-Open No. 2002-372354, a refrigerator is driven during nighttime thereby storing ice in a storage tank utilizing cheaper nighttime electricity. The cold energy of the ice thus prepared during the nighttime is utilized during the daytime by circulating cold water melted from the ice within a cold water showcase. Further, a coil is arranged around the cold water showcase and refrigerant is circulated through the coil. Therefore, the cold water showcase serves as an evaporator for the refrigerator.
In addition, Japan Patent Laid-Open No. 11-223449 discloses a cooling system comprising: a chiller unit for cooling brine to prepare ice: a heat exchanger for exchanging heat between the cooling system and the chiller unit; and an ice storage tank. According to the teachings of Japanese Patent Laid-Open No. 11-223449, the cooling system is connected with both of the heat exchanger and the chiller unit. The ice in the storage tank can be used to keep the cooling system at a low temperature in the form of cool water. Therefore, the cooling system taught by Japanese Patent Laid-Open No. 11-223449 can be kept at a low temperature not only by the chiller unit but also by the cold energy of the ice. In addition, it is also possible to cool down the cooling system using both of the chiller unit and the ice in the storage tank. According to the teachings of Japanese Patent Laid-Open No. 11-223449, the chiller unit is also operated to prepare the ice during the nighttime utilizing cheaper nighttime electricity.
Further, Japanese Patent Laid-Open No. 7-4800 discloses a heat pipe type supercooling ice making equipment comprising: a heat pipe; a jacket for circulating refrigerant from a refrigerator arranged on an upper part of the heat pipe; a heater arranged on a lower part of the heat pipe; a coil-shaped resin tube for letting water therethrough which is wound around the heat pipe; an ice heat storage device (i.e., a tank); and a supercooled water destructing plate to which the water discharged from the tube is dropped. According to the teachings of Japanese Patent Laid-Open No. 7-4800, the water is circulated between the tube and the ice heat storage device while driving the refrigerator using nighttime electricity. Consequently, the heat pipe is activated as a heat exchanger, and the water flowing through the tube is supercooled. The water thus supercooled is discharged from the tube and collide against the supercooled water destructing plate and is frozen.
However, according to the cold storage taught by Japanese Patent Laid-Open No. 60-207877, cold energy of the ice in the ice making pit may be radiated to the atmosphere through the soil around the ice making pit when the external temperature is higher than a coagulation temperature.
Meanwhile, according to the teachings of Japanese Patent Laid-Open No. 2002-372354 and No. 11-223449, the chiller unit is the only cooling means storing the cold energy. Therefore, in case the chiller unit has some kind of trouble or in case of power outage, the cooling systems taught by Japanese Patent Laid-Open No. 2002-372354 and No. 11-223449 are unable to perform their cooling function.
Also, the ice making equipment taught by Japanese Patent Laid-Open No. 7-4800 cannot make ice in case the refrigerator is in trouble or in case of power outage. In addition to the above-explained disadvantage, according to the teachings of Japanese Patent Laid-Open No. 7-4800, the cold energy in the ice heat storage device cannot be transported in case the water therein is completely frozen.